Underground caverns of hydropower project have significant mechanical properties of high stress, high sidewall, large span, complex geological conditions and mutual disturbance of adjacent cavern construction, resulting in very complex deformation and rupture characteristics. Through the laboratory triaxial compression experiments, the mechanical response of deformation and failure mechanism of granite is explored, and the elastic-brittle mechanical properties are also revealed. With the help of high precision microseismic (MS) monitoring system, the inoculation law of the internal fracture initiation, expansion, intersection and penetration of the surrounding rock is captured, and the inoculation mechanism of the rock macroscopic damage is also clarified. The research results of this paper enrich the database of rock mass failure cases of rock cavern, which can provide support for the control of rock mass fracture.